This invention relates generally to irrigation sprinklers of the type having a rotary driven spray head mounted at the upper end of a pop-up riser. More particularly, this invention relates to an improved irrigation sprinkler having a gear drive transmission for rotatably driving the pop-up spray head, and incorporating an improved reverse mechanism for quickly and easily setting the sprinkler for part-circle spray head rotation between a pair of individually adjustable end trip stops, or for continuous full circle rotation. The reverse mechanism further provides improved resistance to vandal-caused damage such as attempted forced rotation of the spray head beyond one of the end trip stops.
Pop-up irrigation sprinklers are well known in the art particularly for use in irrigation systems wherein it is necessary or desirable to embed the sprinkler in the ground so that it does not project appreciably above ground level when not in use. In a typical pop-up sprinkler, a tubular riser is mounted within a generally cylindrical upright sprinkler housing or case having an open upper end, with a spray head carrying one or more spray nozzles mounted at an upper end of the riser. In a normal inoperative position, the spray head and riser are spring-retracted substantially into the sprinkler case so that they do not extend or project a significant distance above the case or the surrounding ground level. However, when water under pressure is supplied to the sprinkler case, the riser is displaced upwardly to shift the spray head to an elevated spraying position spaced above the sprinkler case. The water under pressure flows through a vertically oriented nozzle passage in the riser to the spray head which includes one or more appropriately shaped spray nozzles for projecting a stream or streams of irrigation water generally radially outwardly over a surrounding terrain area and associated vegetation.
In many pop-up sprinklers, a rotary drive mechanism is provided within the sprinkler case for rotatably driving the spray head through continuous full circle revolutions, or alternately back and forth within a predetermined part-circle path, to sweep the projected water stream over a selected target terrain area. In one common form, the rotary drive mechanism comprises a water-driven turbine which is rotatably driven by at least a portion of the water under pressure supplied to the sprinkler case, wherein this turbine rotatably drives a speed reduction gear drive transmission coupled in turn to the rotary mounted spray head. A pair of end trip stops is normally provided to engage and operate a reverse mechanism for reversing the direction of spray head rotation upon movement to the opposite end limits of a predetermined part-circle arcuate path of motion, with at least one of these end trips stops normally being positionally adjustable to variably select the permitted range of spray head motion. In addition, means are normally provided for selectively disabling one of these end trip stops to achieve continuous full circle spray head rotation, if desired. For examples of rotary drive sprinklers of this general type, see U.S. Pat. Nos. 4,787,558; and 5,383,600. Such sprinklers are commercially available from Rain Bird Sprinkler Mfg. Corp. of Glendora, Calif. under the product designations T-Bird Series, 3500 Series, R-50 Series, Falcon, and Talon.
Rotary gear drive sprinklers of this general type beneficially provide relatively accurate and controlled delivery of irrigation water with a substantially uniform water distribution over a target terrain area. However, such sprinklers have not been totally satisfactory.
In accordance with the invention, an improved gear drive sprinkler is provided with a rotatably driven pop-up spray head for delivering one or more outwardly projected streams of irrigation water to surrounding terrain and vegetation. The sprinkler includes a reverse mechanism for reversing the direction of spray head rotation back-and-forth movement through a part-circle path between a pair of individually adjustable end trip stops. The reverse mechanism is resistant to vandal-caused damage such as an attempt to manually force-rotate of the spray head beyond one of the pre-set end trip stops. In that event, a releasible clutch disengages to permit such over-rotation of the spray head without damage to sprinkler components. Upon release of the spray head, the spray head is rotatably driven back to within the pre-set part-circle path whereupon the releasible clutch re-engages for resumed reversible movement between the pre-set end trip stops.
In a preferred form on the invention, the pop-up spray head is mounted at the upper end of a tubular riser which is in turn mounted within a hollow sprinkler housing or case for pressure responsive pop-up movement from a normal position retracted substantially within the sprinkler housing to an elevated spraying position. A water-driven turbine is rotatably driven by inflow of water under pressure into the sprinkler housing, and this turbine is linked via a speed reduction gear drive transmission to the spray head for rotatably driving the spray head at a selected rotational speed. A flow regulator unit is desirably provided at an upstream side of the turbine for bypassing a portion of the water inflow past the turbine in a manner to maintain a substantially constant rotational turbine speed.
The reverse mechanism comprises a lower shift cartridge including a shiftable deflector plate positioned at the upstream side of the turbine. This deflector plate includes at least one and preferably multiple sets of angularly oppositely oriented jet nozzles for imparting a forward-drive or a reverse-drive circumferential swirl to the water flow directed to the turbine. The deflector plate is movable between a forward-drive position for circumferentially swirling the water flow to drive the turbine in one direction, and a reverse-drive position for circumferentially swirling the water flow to drive the turbine in an opposite direction. At least one and preferably multiple over-center springs are provided to retain the deflector plate in the selected forward-drive or reverse-drive position.
The reverse mechanism further includes an upper trip unit mounted within the spray head. The upper trip unit comprises a trip core linked via an elongated trip rod to the deflector plate for shifting the deflector plate between the forward-drive and reverse-drive positions. The trip core is engaged by a pair of end trip stops which rotate with the spray head. The positions of the two end trips stops are individually adjustable to permit spray head rotation back-and-forth within a part-circle arcuate path in any selected azimuthal direction and pattern width. Upon engagement of an end stop with the trip core, the trip core is rotatably driven through a short stroke sufficient to shift the deflector plate in a manner reversing the direction of spray head movement.
In accordance with a primary aspect of the invention, the upper trip unit of the reverse mechanism includes the reversible clutch adapted to disengage upon attempted forced over-rotation of the spray head. In one preferred form, the reversible clutch comprises a clutch plate mounted at an upper end of the trip rod, in combination with a clutch spring for normally urging the trip core and clutch plate into rotatably engaged relation. In the event that the spray head is manually force-rotated beyond either one of the two end trip stops with a force exceeding the engagement force applied by the clutch spring, the trip core and clutch plate disengage to permit such over-rotation without damage to components such as the end trip stops. Upon resumed operation, the sprinkler spray head will be rotatably driven back to a position within the pre-set arcuate path, whereupon the trip core and clutch plate will re-align and re-engage for resumed spray head movement within the pre-set arcuate pattern.
The improved sprinkler further includes an adjustment cam mounted within the spray head and accessible from the exterior thereof for selectively disabling one or both of the end trip stops, for setting the spray head for continuous full circle revolutions. The adjustment cam includes at least one cam pin engageable with the reverse mechanism. In one preferred form, the adjustment cam is engageable with the trip core for disengaging the trip core from the associated clutch plate to effectively disable both end trip stops. In an alternative preferred form, the adjustment cam is adapted to disengage a trip spring associated with one of the end trip stops. In either case, disablement of one or both of the end trip stops disconnects the upper trip unit from the lower shift cartridge for at least one direction of spray head movement, resulting in spray head rotation through repeated full circle revolutions.
The improved gear drive sprinkler of the present invention may further include an improved plug seal member for closing and sealing an auxiliary inlet to the sprinkler housing. The plug seal member comprises a plug core threadably fitted into an adapter sleeve fixed into the auxiliary inlet to the housing. The adapter sleeve includes a pliant seal lip disposed generally at an inboard end of the plug core, wherein this pliant seal lip is designed for pressure-caused deformation upon supply of water under pressure to the housing interior. The pressure-deformed seal lip is forced against the inboard end of the plug core, into sealing relation therewith, to prevent undesired water leakage from the sprinkler housing through the auxiliary inlet.
In accordance with a further feature of the invention, the improved sprinkler may include means for temporarily supporting the pop-up riser in a partially elevated position to facilitate service and maintenance, such as replacement of one or more spray nozzles mounted on the spray head. In this regard, the pop-up riser includes a lower peripheral flange having at least one gap formed therein for registry with a vertically elongated internal guide rib formed within the sprinkler housing to prevent riser rotation relative to the sprinkler housing. However, the guide rib additionally includes a gap formed therein at a generally mid-height location. The riser can thus be manually elevated to align the flange thereon with the rib gap, whereupon the riser can be rotated through a short part-circle stroke to position a portion of the flange within the rib gap. In this position, the rib will support the riser in a mid-height position for facilitated access to and service of sprinkler components.
The water-driven turbine may also include a brake means for limiting turbine rotational speed, particularly wherein compressed air is used to flush components of the sprinkler system. The brake means comprises at least one and preferably a pair of balanced centrifugal brake arms adapted to displace radially outwardly against a turbine housing or shroud in response to turbine rotation above a predetermined threshold level. The frictional engagement of the brake arms with the turbine housing or shroud effectively restricts turbine rotational speed to prevent excess wear or component damage attributable to compressed air flush-out or the like.
Other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.